Objective: The aim of this study is to identify specifically the DNA of bacterial biofilm on neurostimulation systems using polymerase chain reaction (PCR).

Background: Bacterial biofilm formation on the surface of any implanted device may be associated with infection close to the implants necessitating device removal.

Methods: Forty-five impulse generators (IPGs) were aseptically removed during routine surgery for battery replacement in 36 patients with implanted neurostimulation systems. The devices were stored immediately at -80°C under sterile conditions. To determine the presence of bacterial, the IPGs were processed and DNA was extracted. 500-bp fragments of purified DNA were amplified using universal primers which target hypervariable regions within the bacterial 16S rRNA gene. In the following Single Strain Conformation Polymorphism (SSCP) analysis, genetic information of different bacterial species were separated from each other, isolated, re-amplified, and finally identified using sequencing methods.

Results: On the surface of 3 IPGs (deep brain stimulator, n=2; occipital nerve stimulator, n=1), which were collected from 3 patients (mean age, 42 years) PCR detected DNA of gram-positive bacterial. The specimens were derived from staphylococcus epidermidis (n=1), lactobacillus iners et crispatus (n=1), and bacillus sp. (n=1). The mean interval between implantation and removal was 14.0 ± 8.1 months. Following the initial implantation, antibiotics had been administered in all patients (Cefazolin, n=3). In the follow-up, there had been no occur infection nor wound healing impairment in these three patients. Ten IPGs were removed from 7 patients due to infection. PCR/SSCP detected DNA of Staphylococcus aureus on the surface of 2 deep brain stimulators (DBS), which were removed from 2 patients

Characteristics of patients with positive results of PCR/SSCP analysis

	without manifestation of infection	with manifestation of infection
Number of patients	5 (2m, 3w)	2 (2w)
Mean age	41.6 +/- 17.0 years	54.5 +/- 10.6 years
Number of removed devices	5	2
Diagnosis	dystonia (n=3), neuropathic pain (n=1), occipital neuralgia (n=1)	dystonia (n=2)
Mean time interval implantation-removal	23.2 +/- 21.4 months	2.0 +/- 0.0 months

“. Both patients underwent a total of 4 surgeries respectively due to recurrent infections prior to and after removal of the investigated IPGs. The microbiological culture findings from intraoperative swabs samplings also revealed species belonging to the genus Staphylococcus (Staphylococcus aureus and coagulase-negative Staphylococcus).

Conclusions: Our data shows that biofilm formation with possibly pathogenic bacterial was occur on neurostimulation systems even in patients with well-healed wounds and despite administration of prophylactic antibiotics.

WSSFN Interim Meeting, Mumbai, 3-6 September, 2015.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/bacterial-biofilm-formation-on-neurostimulation-systems/